Effects of labile carbon on anaerobic decomposition processes in permafrost wetlands

<p>Climate warming and permafrost thaw are exposing the large carbon (C) pools of northern wetlands to enhanced decomposition, potentially increasing the release of the greenhouse gases carbon dioxide (CO<sub>2</sub>) and methane (CH<sub>4</sub>). Permafrost thaw is usually associated with changes in hydrology and vegetation: Ground collapse leads to the formation of new, productive thermokarst wetlands, and active layer deepening allows plant roots to penetrate to deeper soil layers. These processes promote interaction between old permafrost carbon and recent plant-derived carbon, but the effect of this interaction on anaerobic decomposition processes is poorly known.</p><p>Here, we report the preliminary results of a 1+-year-long soil incubation experiment where we investigated the role of fresh organics on anaerobic decomposition in arctic wetlands. We sampled mineral subsoil of Greenlandic wetland sites and the active layer and permafrost peat in a Swedish palsa mire, and incubated them with and without repeated amendments of <sup>13</sup>C enriched glucose and cellulose. We determined the rate and isotopic composition of CO<sub>2</sub> and CH<sub>4</sub> with an isotopic laser, and estimated the contribution of soil organic matter decomposition vs. added carbon to the total C gas release. These results represent new understanding on how plant-derived organics change the magnitude and composition of C gas, thus affecting the climatic feedbacks from permafrost wetland C pool.</p>

Perspectives of anaerobic decomposition of biomass for sustainable biogas production: A Review

Biogas production from biomass is an eco-friendly approach that offers renewable energy generation, waste recycling, biofertilizer production along with maintaining environmental quality. Anaerobic decomposition is a familiar practice used for biogas production in worldwide, whereas only few substrates were convenient for attaining desired methane concentration in biogas. Hence, further advancements are necessary for the exploration and utilization of various complex organic materials for the purpose. This article gives a clear outlook on potential of various biomass for biogas production, necessity of pretreatment, applicability of microbial/enzyme addition, maintenance of various process parameters, formulation of suitable digester designs and future scope of this area. The livestock wastes and agricultural wastes possess high energy generation potential (71%) and sustainable utilization of such wastes are admirable to commercialize biogas production in future. Hence, selection of biomass through biochemical methane potential (BMP) analysis and biomass pretreatment prior to anaerobic decomposition is adequate to improve the quality and quantity of generated biogas. Addition of effective microorganisms or respective enzymes along with the employment of suitable bioreactors, are other perspectives to enhance decomposition. The single-stage and multi-stage systems possess much attention than other types of reactors since that offers accurate process management at four different stages of decomposition. Moreover, the maintenances of optimum pH, temperature, volatile fatty acids, carbon/nitrogen ratio, etc. are crucial to evade system unsteadiness during decomposition. Since comprehensive mathematical models are appropriate to make the anaerobic decomposition process economically feasible and advancement with these forecasts are adequate to commercialize this technology in the future.

Pengaruh Penambahan Lumpur PDAM dan Zeolit sebagai Media Imobilisasi Bakteri terhadap Produksi Biogas dari Limbah Organik Pasar (Effect of Addition PDAM Sludge and Zeolite as Bacterial Immobilization Media on Biogas Production from Organic Waste)

Organic waste can be processed into biogas through the anaerobic decomposition process. Anaerobic decomposition can be influenced by various factors including the addition of immobilization media. Cell immobilization is an attempt to increase the stability of the anaerobic process while reducing the potential for washout. Adding this solid material can increase reactor efficiency and can increase methane yield. The research on the addition of zeolite and PDAM sludge as immobilization media aims to find out how the effect of the addition of immobilized media, as well as the best composition between PDAM slurry and zeolite as immobilization media in the biogas production process from organic waste. The immobilization media used has three variations in the composition ratio between PDAM sludge and zeolites, namely 2:0, 2:1, 1:1 and a control reactor. Observation parameter are of VS, pH, concentration of methane gas and gas volume. Based on observations made, it was known that the addition of zeolite and sludge PDAM as a medium of immobilization in the biogas production process could increase biogas production and the concentration of methane produced. Of the three variations in the composition of the media used in this study, the composition ratio of 2: 1 gave the best biogas production results in the amount of 23.2844 L. As for the methane concentration, the overall reactor with the addition of immobilization media results in higher biogas concentrations and the reactor with the addition of media with a ratio of 2: 1 gave the largest methane concentration results. Keywords: biogas, immobilization, PDAM Sludge, zeolite Abstrak Sampah organik pasar dapat diolah menjadi biogas melalui proses penguraian anaerobik. Penguraian anaerobik ini dapat dipengaruhi oleh berbagai faktor diantaranya penambahan media imobilisasi. Imobilisasi sel adalah salah satu usaha untuk meningkatkan stabilitas proses anaerob sekaligus mengurangi potensi washout. Penambahan material padatan ini dapat meningkatkan efisiensi reaktor dan dapat meningkatkan yield metana. Penelitian bertujuan untuk mengetahui bagaimana pengaruh penambahan media imobilisasi tersebut, serta komposisi terbaik antara lumpur limbah PDAM dan zeolit sebagai media imobilisasi pada proses produksi biogas dari limbah pasar. Media imobilisasi yang digunakan memiliki tiga variasi perbandingan komposisi antara lumpur PDAM dan zeolit, yaitu 2:0, 2:1, 1:1 dan reaktor kontrol. Parameter pengamatan adalah nilai VS, pH, konsentrasi gas metana, dan volume gas. Berdasarkan hasil pengamatan yang dilakukan diketahui bahwa penambahan zeolit dan lumpur PDAM sebagai media imobilisasi pada proses produksi biogas dapat meningkatkan produksi biogas serta konsentrasi metana yang dihasilkan. Dari tiga variasi perbandingan komposisi media yang digunakan dalam penelitian ini, perbandingan komposisi 2:1 memberikan hasil produksi biogas terbaik yaitu sebesar 23,2844 L. Sedangkan untuk konsentrasi metana, reaktor dengan penambahan media imobilisasi menghasilkan konsentrasi biogas yang lebih tinggi dengan hasil terbaik yaitu variasi perbandingan 2:1. Kata kunci: biogas, immobilisasi, lumpur PDAM, zeolit

Anaerobic Decomposition of Cattle Manure Blended with Food Waste for Biogas Production

The concern on how food and livestock waste should be managed and recycled has greatly increased in the world. This research investigated the anaerobic decomposition (digestion) process for biogas production on dairy cattle manure (CM) and food waste (FW) using a bacteria as inoculum - Pseudomonas aeruginosa. CM and FW were co-digested with bacteria (P. aeruginosa) as the substrate. FW was allowed to decompose separately without inoculum for 30 days. Digesters (Bioreactor) were prepared in five places to monitor the maximum biogas production, generation rate of methane and number of days for the production of biogas. 1 to ratio 5ml and 10ml of FW were codigested with P. aeruginosa (bacteria) in 2 proportion and also Cow manure with 1 to ratio 1 and 0.5ml in 2 proportions [ 1:5ml; 1:10ml and 1:1; 1:5ml]. Batch process operation was used under mesophilic condition (35⁰C) for the digesters/bioreactor. Production of biogas was notices on the third and fourth day after commencement for the digesters with cattle manure, fourth to fifth day for the digester (bioreactor) with bacteria and third day for the digester with only FW. FW and CM generated highest cumulative biogas with volume of 88.5g/kg.

PengaruhPenggunaanSubstrat pada Pengomposan Secara Anaerob Menggunakan Tandan Kosong Kelapa Sawit (TKKS) dari Limbah Media Jamur Merang

The anaerobic decomposition process of organic matter in EFB from straw mushroom media waste with the addition of substrates from manur, sludge, EM4 and POME is an alternative treatment of organic material by producing compost and biogas. This study aims to determine the effect of the use of substrate in the composting process of EFB from the waste media of straw mushrooms and the content of chemical nutrients in compost EFB with anaerobic fermentation. The composting process is carried out by inserting EFB in anaerobic bioreactors and adding substrates containing the starter. During the decomposition process observations were carried out every week and every two weeks. The parameters analyzed are temperature, pH, C/N, available P, K-dd and biogas volume. The results showed that the anaerobic organic matter decomposition process carried out for 8 weeks contained the highest biogas production when treated using a substrate from EM4 with a biogas volume of 10L / day with temperatures reaching 30oC having a pH characteristic of 8.79; Nitrogen 1.04 - 1.68%, C-organic 15.30%, C / N 11.71, P-available 0.69 and K-dd 1.13%.

Dispersion is essential in crop residue application

Background: Crop residue application can maintain soil fertility and sustain agriculture. However, the effects of residue application are unstable because of variable weather conditions and the residual effects of crop residue application. Furthermore, residue application often reduces crop yields. Therefore, I tried to clarify effective residue application factors in an environment which was has stable weather conditions and low residual effects. Methods: Majuro atoll, a coral sand atoll near the equator, was selected for the experiment site because of its stable weather and low residual effect of coral sand. A factorial design experiment using sweet corn was conducted based on the following four factors: fungi propagation before application, cutting residue into pieces, dispersion (or accumulation) of applied residue, and placement (on the surface or incorporation) with an equal amount of crop residue. The effects of each factors on the corn yields were evaluated using Cohen’s power analysis. Results: The dispersion showed the largest effect (1.2 in Cohen’s), which exceeded the effect of incorporation (0.7). The interaction of dispersion and incorporation showed a huge effect (4.9) on corn yield. Discussion: The effect of dispersion was not positive but it avoided the negative effects of residue clustering. Because, the toxicity of the plant residue and generation of toxic substances by anaerobic decomposition are widely known. Anaerobic decomposition occurs inside the residue clusters. However, dispersion reduced the toxicity by adsorption in soil and avoiding anaerobic decomposition. Furthermore, incorporation showed an interaction effect, but surface placement did not. Conclusion: The dispersion of crop residue enhanced the positive effect of crop residue incorporation by avoiding the toxicity from crop residue. This finding adds a new viewpoint for the controversy between conventional and conservation agriculture

Anaerobic Co-Digestion of Human Excreta and Corn Stalk for Biogas Production

The anaerobic decomposition process of human feces substrate with a C/N ratio of 14.6 has failed to produce biogas optimally. In order to produce biogas maximally, the C/N ratio in the substrate should be in the range of 20-30. In this study, a combination of human feces substrate (C / N = 14.6) with corn stalk waste (C / N = 66.5) was carried out. Corn stalks were soaked first in a NaOH solution to separate lignin before being mixed with human feces. In this study the effect of the C/N ratio from the combination of feces and corn stalks as well as the effect of the type of activated sludge on the rate of biogas production were evaluated. The C/N ratios were varied at 20, 25, and 30 with F/M of 0.5. As the source of microbes is the activated sludge of human feces. A further experiment was carried out by varying the types of microbes where sludge from cow's rumen, activated sludge from feces, and activated sludge from rotten corn stalk was employed at a C/N ratio of 30 and F/M of 0.5. The results of this study showed that the optimal biogas production was obtained at a C/N ratio of 30 with a cumulative gas volume of 13.185 ml for 60 days. The type of microbes that produce maximum biogas production was the activated sludge from the rumen. The optimum biogas yield was obtained at 4.184 liters/kg COD, which was achieved in the stationary phase with a C/N ratio of 30.Keywords: anaerobic co-digestion; biogas; corn stalk; human feces

Enhancement of Substrate Decomposition through Potential Hydrolytic Bacteria for Cumulative Biogas Production

Scenarios focus on the practical behavior of anaerobic decomposition systems to enhance biogas production, in addition to assure economic progression and ecological sustainability. The present study has framed to identify the potential hydrolytic bacteria from five different sources since principally the efficacy of hydrolytic bacteria determines the rate of hydrolysis of anaerobic decomposition and thereby biogas production. Among the 40 dominant bacteria isolated from diverse bases, 10 isolates were selected as efficient through preliminary screening. Consequently, the premier enzyme activity obtained from the isolate G5 obtained from goat rumen fluid for cellulase (44.16±1.00 U/ml), protease (260.63±1.35 U/ml) and lipase (33.20 ± 0.81 U/ml). Morphological, biochemical and molecular characterization revealed that G5 is Bacillus sp. DDG5 (KM093856.1). A range of pH (7.0-7.5) and temperature (40oC) was sufficient for the highest activity of hydrolytic enzymes experienced. Biogas production using cow dung showed an improved efficiency of 9.54 % in Bacillus sp. DDG5 treated tank (70.16 ± 1.54 %) in contrast to control (58.13 ± 1.02%) at 30th day. However, this study established that Bacillus sp. DDG5 obtained from goat rumen fluid is the promising hydrolytic bacteria, since it can be applied for proficient hydrolysis of various organic materials to enhance methane production in outlook. Int. J. Appl. Sci. Biotechnol. Vol 6(4): 386-396